Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1–2
Triggering a persistent slab avalanche on upper elevation north and east aspects is unlikely, but not impossible. A poor snowpack structure exists where weak, old facets are buried 1 to 3 feet deep under a slab.
Without significant new snow, the sensitivity of the facets is decreasing as the slab above them becomes less cohesive. Obvious signs of instability, like recent avalanches, cracking, and collapsing, are becoming hard to find. However, that does not mean the snowpack is trustworthy.
Dig into the snow, and look for weak or sugary snow beneath a denser slab. If you find this poor structure, consider sticking to slopes under 30 degrees.